How would you describe Polk’s stated and unstated reasons for going to war? How do they differ?

"American blood has been shed on American soil" was much more legitimate than the "Al Qaeda is in Iraq" line which half the Democrats in Congress spinelessly endorsed in 2002. It was not main reason for war with Mexico in 1946, but Polk did at least try alternatives (offering to buy New Mexico and California). Self-defense can be a legitimate reason, and Polk at least made a credible attempt to go through the motions of making a case.